Iamblichus' Life of Pythagoras

...at another by Pherecydes the Syrian, and at another by almost all those who presided over sacred concerns, to whom he earnestly recommended Pythagoras, so that he might be sufficiently instructed in divine matters. He was educated in such a way as to be, fortunately, the most beautiful and godlike of all those celebrated in the annals of history. Upon the death of his father, though he was still a youth, his aspect was most venerable and his habits most temperate, so that he was revered and honored even by elderly men. He drew the attention of all who saw and heard him, appearing as an admirable person to everyone who beheld him. Hence, it was reasonably asserted by many that he was the son of a God.

Strengthened by this reputation, by the education received from infancy, and by his naturally godlike appearance, he demonstrated even more that he deserved these distinctions. He was adorned by piety, rigorous disciplines, a transcendently good lifestyle, firmness of soul, and a body in due subjection to the mandates of reason. In all his words and actions, he discovered an inimitable quiet and serenity; he was not subdued at any time by anger, laughter, emulation, contention, or any other perturbation or rashness of conduct. Instead, he lived at Samos like a beneficent spirit. Hence, while he was still a youth, his great renown reached Thales at Miletus and Bias at Priene—men illustrious for their wisdom—and extended to the neighboring cities. To all this, we may add that the youth was everywhere celebrated as the "long-haired Samian" and was revered by the multitude as one under the influence of divine inspiration. But after he had reached his eighteenth year, around the period when the tyranny of Policrates first appeared, he foresaw that under such a government...